#include <REGX52.H>
void delay_ms(unsigned int ms)
{
    unsigned int i, j;
    for (i = 0; i < ms; i++)
    {
        for (j = 0; j < 123; j++)
            ;
    }
}
void main()
{
    unsigned int i;
    P3=0x00;
    while(1)
    {
        for (i=0;i<8;i++)
        {
            P2=~(0x01<<i);
            delay_ms(500);
        }
        P2=0xFF;
        for (i=0;i<8;i++)
        {
            P3=0x01<<i;
            delay_ms(500);
        }
        P3=0x00;
    }
}